Beam Aperture Layout for Uniform Charged-Particle Writing Paths
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Solution Overview
Problem
Existing charged particle lithography systems lack sufficient throughput and do not provide an optimum arrangement of sub-beams or beamlets for uniform exposure of the wafer surface.
Innovation Solution
A beamlet aperture array with a non-regular hexagonal pattern of sub-beam apertures, where each aperture is uniformly spaced along a line parallel to a different direction, and beamlet apertures arranged in groups with unbalanced and shifted configurations to form separate, evenly spaced writing paths on the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a regular array arrangement of beamlet apertures is used, then the device structure is simple and easy to manufacture, but the writing paths overlap and exposure uniformity deteriorates
Solution Approach 1:
The patent applies asymmetry by using an unbalanced array configuration where rows have different numbers of beamlet apertures (e.g., 7, 8, 9, 10 apertures per row) and columns are shifted relative to each other. This asymmetric arrangement prevents writing path overlap while maintaining manageable device complexity, directly resolving the contradiction between exposure uniformity and device complexity.
2Productivity
If more beamlets are used to increase throughput, then productivity improves, but the arrangement complexity increases and uniform spacing becomes difficult to maintain
Solution Approach 1:
The patent segments the beamlet aperture array into multiple rows with different numbers of apertures (7, 8, 9, 10 apertures per row) and groups them into beamlet groups. This segmentation allows increasing the total number of beamlets for higher throughput while organizing them in a structured manner that maintains uniform spacing and manageable complexity.
Solution Approach 2:
The patent introduces a second directional dimension for uniform spacing by arranging beamlets such that they are uniformly spaced when projected onto a line parallel to the third direction (different from the scanning direction). This dimensional approach enables increased beamlet density for higher throughput while maintaining uniform exposure patterns.
3Manufacturing precision
If beamlet apertures are aligned in regular rows and columns, then the array is easy to manufacture, but writing paths overlap and exposure precision deteriorates
Solution Approach 1:
The patent employs asymmetric column shifting where columns are offset by different amounts (e.g., first column shifted by amount A, second column by amount B) rather than uniform spacing. This asymmetric configuration prevents writing path overlap for precise exposure while remaining manufacturable through standard aperture fabrication techniques.
Solution Approach 2:
The patent applies local quality by giving different characteristics to different parts of the array: rows have different numbers of apertures, columns have different shift amounts, and beamlet groups have specific configurations. This localized variation optimizes exposure precision in each region while maintaining overall manufacturability.
Data Source
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AI summary
A sub-beam aperture array for forming a plurality of sub-beams from one or more charged particle beams. The sub-beam aperture array comprises one or more beam areas, each beam area comprising a plurality of sub-beam apertures arranged in a non-regular hexagonal pattern, the sub-beam apertures arranged so that, when projected in a first direction onto a line parallel to a second direction, the sub-beam apertures are uniformly spaced along the line, and wherein the first direction is different from the second direction. The system further comprises a beamlet aperture array with a plurality of beamlet apertures arranged in one or more groups. The beamlet aperture array is arranged to receive the sub-beams and form a plurality of beamlets at the locations of the beamlet apertures of the beamlet array.